An artist's conception of the LADEE spacecraft hitting the moon's surface. / NASA

by Traci Watson, Special for USA TODAY

by Traci Watson, Special for USA TODAY

Some spacecraft end their days abandoned on a planet's surface. Others are left to fly in ceaseless circles. But the NASA spaceship called LADEE will end its days with a bang, not a whimper.

On April 21 or thereabouts, LADEE will make a kamikaze dive into the far side of the moon, ending a successful seven-month mission to study the wispy lunar atmosphere. A fatal impact has long been in the cards for the $280 million craft, which is carrying too little fuel to either escape the moon's vicinity or park the spacecraft in a higher orbit.

The spaceship's end will be "bittersweet," LADEE project manager Butler Hine of NASA's Ames Research Center said at a news conference Thursday. "You're both very proud of the success and you're also a little melancholy that you won't be talking to your spacecraft again."

After launching in September, the vending-machine-size spaceship has been gathering data about the moon's vanishingly thin atmosphere. The spaceship's instruments sniffed out traces of neon, aluminum and many other substances wafting around the moon, and it also "discovered a dust veil that enshrouds the moon perpetually," says LADEE project scientist Rick Elphic, also of Ames. That dust veil comes from the tiny space rocks that rain down on the moon, kicking up puffs of the gray lunar dust when they land.

During its brief working life, LADEE - short for Lunar Atmosphere and Dust Environment Explorer - was maneuvered so precisely that it has reached old age with a little more fuel than expected. To take advantage of that extra oomph, the spacecraft will skim just 1 to 2 miles above the lunar surface to gather even more science data, hopefully avoiding a jutting ridge along the way before swooping away from the surface once again.

"There is a chance that we could clip a mountain accidentally, but the risk is pretty low," Hine said. "And really, the value of the science we can do with this attempt is worth this risk."

On April 11, the spacecraft's engines will fire one last time. The spacecraft will drop low once again, fly through an eclipse on Tax Day, and gradually droop closer and closer until it slams into the lunar surface on the side facing away from Earth around April 21. Engineers won't immediately know the exact moment of the spacecraft's demise, but LADEE's far-side impact means it has no chance of hitting the historic landing sites of the Apollo spacecraft.

The spacecraft could end up smashing itself against the side of a crater. Or, if it comes down on a plain, it could "skip and roll as it destroys itself," Hine said, potentially leaving a long track that could be detected by NASA's Lunar Reconnaissance Orbiter, a satellite circling the moon.

Regardless of where it hits, "this is a very, very high-speed impact," Elphic said. "There's nothing gentle about it. You will be destroyed."